1. Field of the Invention
This invention relates generally to internal combustion engines and more particularly to internal combustion engines in which opposed pairs of cylinders have coupled or common piston rods. A novel technique for converting the reciprocating motion to rotary motion is used in the engine.
2. Description of the Related Art
It is known in the related art to position cylinders so that motion of the pistons is generally at right angles to the drive shaft. By coupling the piston rods to a crank shaft, the structure of the crank shaft permits the force exerted by the piston rod to be off center and to provide a torque on the shaft causing the crank shaft and the coupled drive shaft to rotate. The positioning of the cylinders so that the piston motion was perpendicular to the drive shaft resulted in a large engine. In addition, the crank shaft is frequently a very elaborate structure that is difficult to fabricate.
The advantages of opposing cylinder pairs, coupled together and operating 180.degree. out of phase, has been recognized. In U.S. Pat. No. 1,765,237, a structure is coupled to the drive shaft of the engine that permits cylinder pairs, that are directly coupled, to travel over the structure while maintaining a constant distance. In another embodiment in the related art, the Bourke engine, in which cylinder pairs have pistons that are coupled together, has apparatus coupling the pistons permitting a section of a crank shaft to move freely in a direction perpendicular to the motion of the pistons. The combination of the motion of the pistons in one direction coupled with the capability of the crank shaft motion in a perpendicular direction, permits the linear motion of the pistons to be converted to circular motion of the crank shaft.
In the 1940's, an engine was developed by Karl Herman, generally referred to as the Herman engine and commercially available as the Dyna-Cam engine, that positioned coupled pistons relative to the drive shaft in a manner that the motion of the pistons was parallel to the axis of the drive shaft. The pistons were coupled to the drive shaft by providing a roller device that engaged a shaped plate cam device coupled to the drive shaft. As the coupled pistons moved back and forth as a result of combustion in the cylinder, the shaped plate cam translated the motion of the coupled pistons into a torque rotating the drive shaft. The torque and force exerted by the shaped plate on the drive shaft make configuration susceptible to failure.
A need has therefore been felt for an internal combustion engine that has at least one pair of cylinders (and having the motion of coupled piston rods) generally parallel to the axis of the drive shaft and in which the coupled or common piston rods are coupled to the drive shaft. In addition, a need was felt for cylinders that have an improved technique for replacing the gases that result from combustion within the cylinder with air.